Omcron, omcron-dialkyl s-(1, 2-dicarbalkoxyethyl) monothiophosphates and miticide compositions containing the same



0,0-DIALKYL S (1,2 Di-CARBALKQXYETHYL) MONOTHIGPHGSPHATES AND MITICIDE COMPOSETIGNS CGNTAINDG THE SAME Gerald A. Johnson, Stamford, Conn, assignor to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Appiication February 18, 1953, Serial No. 337,693

8 Claims. (C1. 167-22) comprise the 0,0 dialkyl S-(1,2-dicarbalkoxyethyl) monothiophosphates represented by the formula -S-GHCO 0R3 RZO/ (IJHZC O 0 R4 in which R1, R2, R2. and R4 each represent an alkyl radical having from one to four carbon atoms.

These monothiophosphate esters may be prepared by nitric acid oxidation of the 0,0-dialkyl S-(1,2-dicarbaikoxyethyl) dithiophosphate esters substantially according to the following equation:

The oxidation of the dithiophosphate esters takes place rapidly and is usually exothermic. The reaction may be effected at temperatures within the range of from about 80 C., and preferably in the range of 40 C. It is also advisable to add the nitric acid portionwise to the dithiophosphate ester and to have some means at hand for cooling the reaction vessel.

Other oxidizing agents which may be employed in the conversion of the dithiophosphate esters to the monothiophosphate esters include hydrogen peroxide, hypochlorous acid, chromic acid, and permanganate in acid or neutral medium.

The 0,0-dialkyl S-(1,2-dicarbalk0xyethy1) dithiophosphates which are utilized in the preparation of the compounds of the present invention, may be produced by methods disclosed in U. S. Patent 2,578,652.

The followim examples wili further illustrate the preparation of the novel compounds of the present invention.

EMMPLE l 0,0-dimethyl S-(J ,Z-dicarbethoxyethyl) monothiophosphate 99.1 g. (0.3 mole) of 0,0-dimethyl S-(l,2-dicarbethoxyethyl) dithiophosphate was placed in a 500 cc. three-necked round-bottomed 1125i; fitted with a mechani- Eatented July 12, 1955 cal glass hook stirrer, a thermometer (immersed in the reaction mixture), and a Y-tube. One neck of the tube was fitted with a dropping funnel for the addition of nitric acid, while the other remained open for the escape of nitrogen dioxide gas. 216 g. (2.4 moles) of nitric acid, sp. gr. 1.42, Was added dropwise during a two and onehalf hour period whiie the temperature of the reaction mixture was maintained between 25 and 31 C. The mixture was then stirred for an additional 1.5 hours at 2830 C. while nitrogen dioxide continued to be evolved. Finally, the mixture was subjected to reduced pressure (water-pump vacuum) for about two hours to remove the last traces of nitrogen dioxide, and then poured over 500 g. of crushed ice. The yellow oil which separated, was extracted with three 100 cc. portions of ether. After washing the extract with five cc. portions of 10% sodium bicarbonate solution and then with three 50 cc. portions of concentrated sodium chloride solution, it was dried over anhydrous magnesium sulfate and stripped free of solvent at 35 C. and 0.5 mm. pressure. The residual yellow oily liquid, weighing 58.4 g. (62% yield), had a refractive index n 1.4696.

AnaL-Calcd. for CtoHrsOrPS: S, 10.20. S, 10.19.

Found:

EXAMPLE 2 0,0-diethyl S- (1,2-dicarbomethoxyethyl) monoth iophosphate The procedure of Example 1 was employed using 54 g. (0.164 mole) of 0,0-diethyl S-(1,2-dicarbomethoxyethyl) dithiophosphate and 119 g. (1.31 moles) of nitric acid, sp. gr. 1.42. The crude product was extracted with two 50 cc. portions of benzene. 19.8 g. of the monothiophosphate ester was obtained. The product was a clear yellow liquid having a refractive index n 1.4680.

AnaL-Calcd. for CioHrsOiFS: S, 10.20. Found: S. 9.72.

EXAMPLE3 0,0-a'z'metlzyl S-(1,2-dicarb0meth0xyelhyl) monothiophosphate The procedure of Example 1 was employed using 58 g. (0.192 mole) of 0,0-dimethyl S-(1,2-dicarbomethoxyethyl) dithiophosphate and 139 g. (1.54 moles) of nitric acid, sp. gr. 1.42. The reaction mixture was poured over g. of crushed ice, and the crude product was extracted with three 50 cc. portions of benzene. 19 g. or" the mono thiophosphate ester was obtained. The product was a pale yellow liquid having a refractive index n 1.4757.

ArzaL-Calcd. for Cal-115071 8: S, 11.21. Found: S, 10.12.

EXAMPLE4 0,0-diethyl S-(1,2-dicarbeth0xyethyl) monothiophosphate EXAMPLE 5 S-(] .z-dicarbethoxyethyl) phosphate 0,0-di-n-pr0pyl monothio- The procedure of Example 1 was employed using 77.3 g. (0.2 mole) of 0,0-di-n-propyl S-(1,2-dicarbethoxy- EXAMPLE 6 0,0-di-n-bulyl S-(l,Z-dicarbo-n-butoxyezltyl) phosphate mmwthio- The procedure of Example 1 was employed using 63 g. (0.134 mole) of 0,0-di-n-butyl S-(LZ-dicarbo-n-butoxyethyl) dithiophosphate and 97.2 g. {1.073 moles) of nitric acid, sp. gr. 1.42. The reaction mixture poured over 200 g. of crushed ice, and the crude product was extracted with a solvent consisting of two parts of benzene and one part of toluene. 45.1 g. (74% yield) of the monothiophosphate ester was obtained. The product was a yellow oily liquid having a refractive inner; L598.

Anal.Calcd. for CzoHzsOrPS: S, 7.05. Found: 5, 6.5.

The present 0,0-dialkyl S-(1,2-dicarbalkoxyethyl) monothiophosphates are somewhat soluble in many organic liquids including the ketones, namely, acetone. cyclohexanone, isophorone. methyl ethyl icetonc. methyl isobutyl ketone and the like; the lower monohydric aliphatic alcohols; ketone alcohols such as diacetone alcohol; various esters, namely, the acetates, phthalates, abietates, fumarates and maleates; and aromatic hydrocarbons such as benzene, toluene and xylene. They are adapted for various uses, more particularly as acaricides. insecticides, antioxidants and petroleum additives. They are of exceptional value as toxic constituents of miticide compositions.

While the monothiophosphate esters of the present invention have been found to be outstanding in the control of mites and larvae and eggs of mites, they are also very effective in controlling such insect pests as aphids. tlarr beetles, milkweed bugs. gcrman cockroaches and southern army worms. The monothiophosphate esters of Examples 1, 2 and 3 above each gave a 100% kill of aphids at a dilution of 1:10;),000 in acetone-water solutions. The monothiophosphate esters of Examples 1, 2, 3 and 4 above also gave a 100% kill. of milkweed bugs and german cocf-e roaches in contact with a 1.0% dust (pyrophyllite used as the carrier).

The 0,0-diall yl S-(1.2-dicarbalkoxyethyl) monothiophosphate esters may be compounded with other materials for the preparation of suitable miticide compositions. For example, they may be admixed with talc. pyrophyllite, bentonite or other inert powders or ducts in concentrations of, say, from 0.5 per cent to 5 per cent and the composition thus formed may be applied as a dust to the mite infested plants, shrubs or trees. Aqueous suspensions and emulsions of the rnonothiophosphate esters may also be employed in combating mites at dilutions of, say, from 121,000 to 1:l00,000. They may, also be compounded with a suitable oil such as pine oil or white mineral oil and applied as an oil spray to the foliage of plants for the purpose of effecting mite control.

The marked activity of the monothiophosphate esters of the present invention in controlling the active stages and eggs of the twospotted spider mite is illustrated in the table below. Experiments were also made using the corresponding dithiophosphate esters at the same dilutions and these results are given in the table. Each test was carried out as follows: The phosphate compound was dissolved in a solvent medium consisting of 65% acetone and Water. The first pair of leaves of a lirna bean plant which were infested with two-spotted spider mites were dipped in the test solution for three seconds, drained l and allowed to dry. The plant was held in a greenhouse for 48 hours after which counts of living and dead mites on one of the leaves were made under a microscope. The percent kill corrected for check mortality was recorded. The plant was then held in the greenhouse for an additional 11' days after which the other leaf was examined and an estimate made of the percentage of eggs killed.

TABLE "ompound Dilution :52 gfi 0,0 dirnethyi S t 1.2 dicarbeth 1-100, 000 active stages..

1-10, 000 eggs 100 c 1-l0, 000 active stages". 99. 0 A, .l1yl)-monothiophosphate. 0.0-dietitvl il.2-diearb0meth- 110,000 68.3

oryethyl)-c1thiophosphate. 0,0-diethyl S- (1,2-diearbometh- 1-10, 000 eggs 99. 0

oxyethyl)-monot.hiophosphate. 0,0-diethyl S 'L2-dicarbometh- 1-10, 000 do 0 bxyethyl)-dithioph0sphate. 7.0 dimethyl S 1,2 dicarbo 1-10, 000 active stages... 82. 2

niothoxyethyl) monothiophosphato. 0,0 litncthyl S t 1,2 cilearbol10,000 d0 8. 0

metltoxyethyl l dithiophosphatc. 0.0 dimethyl S t 1,2 dicarbo- 1-1, 000 eggs 100 methoxycthyl -mon0thioph0sphate. 0.0 dimethyl t 1.2 dicnroo- 11,000 do 25.0

methoxycthyl dithiophosphate.

The results given in the above table clearly illustrate the superiority of the monothiophosphate esters over the corresponding dithiophosphate esters in the control of mites and their eggs.

The compounds of the present invention are characterized also by a pleasant, fragrant aroma in contrast to the corresponding dithiophosphate esters and many other ltnown thiophosphates which have displeasing and disagreeable odors. Thus, the present monothiophosphate esters may be advantageously employed in the household, for example in fly sprays, and in suitable solvents for the impregnation of textiles, and particularly articles of clothing, to provide insect repellency in such articles.

While the invention has been described with particular reference to specific embodiments, it is to be understood that it is not to be limited thereto but is to be construced broadly and restricted solely by the scope of the appended claims.

1 claim:

1. A monothiophosphate ester of the general formula P-S-JJHCOOR;

R20 CHzC-OORt References Cited in the file of this patent UNITED STATES PATENTS Hoegberg Jan. 10, 1950 Cassaday et a1 Jan. 10, 1950 Cassaday et a1 Jan. 10, 1950 Cassaday Dec. 18, 1951 Rudel et a1. July 14. 1953 

1. A MONOTHIPHOSPHATE ESTER OF THE GENERAL FORMULA 